Register      Login
Wildlife Research Wildlife Research Society
Ecology, management and conservation in natural and modified habitats
RESEARCH ARTICLE

Movements and home ranges of radio-tracked Crocodylus porosus in the Cambridge Gulf region of Western Australia

Winston R. Kay
+ Author Affiliations
- Author Affiliations

Department of Zoology & Entomology, The University of Queensland, Brisbane, Qld 4072, Australia. Present address: Nature Conservation Division, Department of Conservation and Land Management, Locked Bag 104, Bentley Delivery Centre, Bentley, WA 6983, Australia. Email: winstonk@calm.wa.gov.au

Wildlife Research 31(5) 495-508 https://doi.org/10.1071/WR04037
Submitted: 10 October 2003  Accepted: 12 May 2004   Published: 13 December 2004

Abstract

VHF radio-tags were attached to 16 estuarine crocodiles that were tracked between October 2001 and May 2003. Male (n = 12) and female (n = 4) crocodiles exhibited distinctly different patterns of movement. Females occupied a small core linear range (1.3 ± 0.9 km) on the main river channel during the dry season and moved up to 62 km to nesting habitat during the wet season, returning to the same core area the following dry season. They occasionally made excursions away from their core areas during the dry season. Males moved considerable distances along the Ord River throughout the year. The largest range recorded was 87 km for a 2.5-m juvenile male. However, ranges of males did not appear to be related to body size, with the largest two ranges being recorded for the smallest (2.5 m) and largest (4.3 m) males tagged. Rates of movement of males did not differ significantly between three size classes of males but there were significant seasonal differences, with the highest mean rates of movement occurring during the summer wet season (4.0 ± 5.4 km day–1). However, males were quite mobile during the dry season and the highest rate of movement detected was 23.3 km day–1 for a 4.3-m male at the end of July. The highest rate of sustained movement was 9.8 km day–1 for a translocated 2.6-m juvenile male, which travelled 118 km in 12 days to return to the area of its capture. Neither males nor females showed exclusive habitat preferences for any of four broad riverine habitats identified on the Ord River. However, the three largest males had activity centres that they returned to frequently despite numerous excursions throughout the year, both up- and downriver. Males had substantial range overlaps with no obvious spatial partitioning, suggesting that territoriality is not an important behavioural characteristic of free-ranging male crocodiles along the Ord River.


Acknowledgments

This work was funded by the Department of Conservation and Land Management (CALM) and Lotterywest through a Gordon Reid Foundation grant to the Save Endangered East Kimberley Species (SEEKS) community group of Kununurra. Additional funding was provided by Australian Geographic. Thanks to numerous volunteers who assisted with fieldwork, particularly Chris Collins, Mike Osborn, Allan Pardoe-Bell and the SEEKS group. I also thank Nick Gales for lending a scanning receiver for an extended period; Derek Goddard, Jack Larsen and Tony Tully for equipment and assistance with helicopter tracking; and Gordon Grigg and Lyn Beard for equipment and advice with aerial tracking from fixed-wing aircraft. Thanks to the CALM office in Kununurra for logistical support during fieldwork, the Wyndham Crocodile Farm for lending their crocodile traps and the Department of Agriculture for the temporary loan of a boat at short notice. Finally, I thank Gordon Grigg, Hamish McCallum and Stuart Halse for their valuable comments during the preparation of this manuscript.


References

Alldredge, J. R. , and Ratti, J. T. (1986). Comparison of some statistical techniques for analysis of resource selection. Journal of Wildlife Management 50, 157–165.
Beard J. S. (1990). ‘Plant Life of Western Australia.’ (Kangaroo Press: Sydney.)

Burbidge A. A. , McKenzie N. L. , and Kenneally K. F. (1991). Nature conservation reserves in the Kimberley, Western Australia. Department of Conservation and Land Management, Perth.

Bureau of Meteorology (1996). ‘Climatic Survey: Kimberley, Western Australia.’ (Australian Government Publishing Service: Canberra.)

Bustard H. R. (1970). Report on the current status of crocodiles in Western Australia. WA Department of Fisheries and Fauna Report No. 6.

Bustard, H. R. , and Choudhury, B. C. (1980). Long distance movement by a saltwater crocodile (Crocodylus porosus). British Journal of Herpetology 6, 87.
Coutinho M. , Campos Z. , Cardoso F. , Massara P. , and Castro A. (2000). Reproductive biology and its implication for management of caiman Caiman yacare in the Pantanal wetland, Brazil. In ‘Crocodilian Biology and Evolution’. (Eds G. C. Grigg, F. Seebacher and C. E. Franklin.) pp. 229–243. (Surrey Beatty: Sydney.)

Davis, L. M. , Glenn, T. C. , Elsey, R. M. , Dessauer, H. C. , and Sawyer, R. H. (2001). Multiple paternity and mating patterns in the American alligator, Alligator mississippiensis.  Molecular Ecology 10, 1011–1024.
Crossref | GoogleScholarGoogle Scholar | Garton E. O. , Wisdom M. J. , Leban F. A. , and Johnson B. K. (2001). Experimental design for radiotelemetry studies. In ‘Radio Tracking and Animal Populations’. (Eds J. J. Millspaugh and J. M. Marzluff.) pp. 15–42. (Academic Press: San Diego, CA.)

Goodwin, T. M. , and Marion, W. R. (1979). Seasonal activity ranges and habitat preferences of adult alligators in a north-central Florida lake. Journal of Herpetology 13, 157–163.
Guillette L. J. Jr , and Milnes M. R. (2000). Recent observations on the reproductive physiology and toxicology of crocodilians. In ‘Crocodilian Biology and Evolution’. (Eds G. C. Grigg, F. Seebacher and C. E. Franklin.) pp. 199–213. (Surrey Beatty: Sydney.)

Hardy A. R. , and Taylor K. D. (1980). Radio tracking of Rattus norvegicus on farms. In ‘A Handbook on Biotelemetry and Radio Tracking: Proceedings of an International Conference on Telemetry and Radio Tracking in Biology and Medicine, Oxford, 20–22 March 1979’. (Eds C. J. Amlaner, Jr, and D. W. Macdonald.) pp. 657–665. (Pergamon Press: Oxford.)

Harris, S. , Cresswell, W. J. , Forde, P. G. , Trewhella, W. J. , Woollard, T. , and Wray, S. (1990). Home-range analysis using radio-tracking data – a review of problems and techniques particularly as applied to the study of mammals. Mammal Review 20, 97–123.
Hooge P. N. (2002). Animal movement analysis Arcview extension, Alaska Biological Science Center, USGS. Available online at http://www.absc.usgs.gov/glba/gistools/animal_mvmt.htm [verified 25 October 2004].

Hooge P. N. , and Eichenlaub B. (2001). Animal movement extension to Arcview. Ver. 2.0. Alaska Biological Science Center, USGS, Anchorage.

Hutton, J. (1989). Movements, home range, dispersal and the separation of size classes in Nile crocodiles. American Zoologist 29, 1033–1049.
Jamerlan M. L. (2003). Establishing mating systems by microsatellite analysis in declining saltwater crocodile (Crocodylus porosus) hatchling production at Edward River Crocodile Farm (north Queensland). M.Sc. Thesis, University of Queensland, Brisbane.

Jessop, T. S. , Tucker, A. D. , Limpus, C. J. , and Whittier, J. M. (2003). Interactions between ecology, demography, capture stress, and profiles of corticosterone and glucose in a free-living population of Australian freshwater crocodiles. General and Comparative Endocrinology 132, 161–170.
Crossref | GoogleScholarGoogle Scholar | Joanen T. , and McNease L. (1970). A telemetric study of nesting female alligators on Rockefeller Refuge, Louisiana. In ‘Proceedings of the 24th Annual Conference of the Southeastern Association of Game and Fish Commissioners’. pp.175–193.

Joanen T. , and McNease L. (1972). A telemetric study of adult male alligators on Rockefeller Refuge, Louisiana. In ‘Proceedings of the 26th Annual Conference of the Southeastern Association of Game and Fish Commissioners’. pp. 252–275.

Kay W. R. (2004). Population ecology of Crocodylus porosus (Schneider 1801) in the Kimberley region of Western Australia. Ph.D. Thesis, University of Queensland, Brisbane.

Kay, W. R. (2005). Crikey: a new method for attaching electronic devices to crocodilians. Herpetological Review ,in press
Kenward R. E. (2001). ‘A Manual for Wildlife Radio Tagging.’ (Academic Press: London.)

Kernohan B. J. , Gitzen R. A. , and Millspaugh J. J. (2001). Analysis of animal space use and movements. In ‘Radio Tracking and Animal Populations’. (Eds J. J. Millspaugh and J. M. Marzluff.) pp. 125–166. (Academic Press: San Diego, CA.)

Kofron, C. P. (1990). The reproductive cycle of the Nile crocodile (Crocodylus niloticus). Journal of Zoology 221, 477–488.
Lance V. A. (1987). Hormonal control of reproduction in crocodilians. In ‘Wildlife Management: Crocodiles and Alligators’. (Eds G. J. W. Webb, S. C. Manolis and P. J. Whitehead.) pp. 409–415. (Surrey Beatty: Sydney.)

Lance, V. A. (1989). Reproductive cycle of the American alligator. American Zoologist 29, 999–1018.
Lang J. W. (1987). Crocodilian behaviour: implications for management. In ‘Wildlife Management: Crocodiles and Alligators’. (Eds G. J. W. Webb, S. C. Manolis and P. J. Whitehead.) pp. 273–294. (Surrey Beatty: Sydney.)

Magnusson, W. E. (1979). Dispersal of hatchling crocodiles (Crocodylus porosus) (Reptilia, Crocodilidae). Journal of Herpetology 13, 227–231.
McDonald N. S. , and McAlpine J. (1991). Floods and droughts: the northern climate. In ‘Monsoonal Australia: Landscape, Ecology and Man in the Northern Lowlands’. (Eds C. D. Haynes, M. G. Ridpath and M. A. J. Williams.) pp. 19–29. (A. A. Balkema: Rotterdam.)

McNease L. , and Joanen T. (1974). A study of immature alligators on Rockefeller Refuge, Louisiana. In ‘Proceedings of the 28th Annual Conference of the Southeastern Association of Game and Fish Commissioners’. pp. 482–500.

Melquist, W. E. , and Hornocker, M. G. (1983). Ecology of river otters in west central Idaho. Wildlife Monographs 83, 1–60.
Messel H. , and Vorlicek G. C. (1987). A population model for Crocodylus porosus in the tidal waterways of northern Australia: management implications. In ‘Wildlife Management: Crocodiles and Alligators’. (Eds G. J. W. Webb, S. C. Manolis and P. J. Whitehead.) pp. 189–198. (Surrey Beatty: Sydney.)

Millspaugh J. J. , and Marzluff J. M. (2001). Radio-tracking and animal populations: past trends and future needs. In ‘Radio Tracking and Animal Populations’. (Eds J. J. Millspaugh and J. M. Marzluff.) pp. 383–393. (Academic Press: San Diego, CA.)

Muñoz, M. D. C. , and Thorbjarnarson, J. (2000). Movement of captive-released Orinoco crocodiles (Crocodylus intermedius) in the Capanaparo River, Venezuela. Journal of Herpetology 34, 397–403.
Powell R. A. (2000). Animal home ranges and territories and home range estimators. In ‘Research Techniques in Animal Ecology: Controversies and Consequences’. (Eds L. Boitani and T. K. Fuller.) pp. 65–110. (Columbia University Press: New York.)

R Development Core Team (2004). ‘R: A Language and Environment for Statistical Ccomputing.’ (R Foundation for Statistical Computing: Vienna.)

Rodda, G. H. (1984a). Homeward paths of displaced juvenile alligators as determined by radiotelemetry. Behavioral Ecology and Sociobiology 14, 241–246.
Rooney A. A. , and Guillette L. J. Jr (2000). Biotic and abiotic factors in crocodilian stress: the challenge of a modern environment. In ‘Crocodilian Biology and Evolution’. (Eds G. C. Grigg, F. Seebacher and C. E. Franklin.) pp. 214–228. (Surrey Beatty: Sydney.)

Rootes, W. L. , and Chabreck, R. H. (1993). Reproductive status and movement of adult female alligators. Journal of Herpetology 27, 121–126.
Ross J. P. (Ed.) (1998). ‘Crocodiles: Status Survey and Conservation Action Plan [online].’ 2nd edn. (IUCN/SSC Crocodile Specialist Group: Gland, Switzerland & Cambridge, UK.)

Ruprecht J. K. , and Rodgers S. J. (1999). Hydrology of the Ord River. Water and Rivers Commission Report No. WRT 24.

Samuel M. D. , and Fuller M. R. (1996). Wildlife radiotelemetry. In ‘Research and Management Techniques for Wildlife and Habitats’. (Ed. T. A. Bookhout.) pp. 370–418. (The Wildlife Society: Bethesda.)

Seymour R. S. , Webb G. J. W. , Bennett A. F. , and Bradford D. F. (1987). Effect of capture on the physiology of Crocodylus porosus. In ‘Wildlife Management: Crocodiles and Alligators’. (Eds G. J. W. Webb, S. C. Manolis and P. J. Whitehead.) pp. 253–257. (Surrey Beatty: Sydney.)

Start, A. N. , and Handasyde, T. (2002). Using photographs to document environmental change: the effects of dams on the riparian environment of the lower Ord River. Australian Journal of Botany 50, 465–480.
Crossref | GoogleScholarGoogle Scholar | Taylor D. (1984). Management implications of an adult female alligator telemetry study. In ‘Proceedings of the Annual Conference of the 38th Southeastern Association of Fish and Wildlife Agencies’. pp. 222–227.

Thom, B. G. , Wright, L. D. , and Coleman, J. M. (1975). Mangrove ecology and deltaic-estuarine geomorphology: Cambridge Gulf–Ord River, Western Australia. Journal of Ecology 63, 203–232.
Walsh B. (1987). Crocodile capture methods used in the Northern Territory of Australia. In ‘Wildlife Management: Crocodiles and Alligators’. (Eds G. J. W. Webb, S. C. Manolis and P. J. Whitehead.) pp. 249–252. (Surrey Beatty: Sydney.)

Walsh, B. , and Whitehead, P. J. (1993). Problem crocodiles, Crocodylus porosus, at Nhulunbuy, Northern Territory: an assessment of relocation as a management strategy. Wildlife Research 20, 127–135.
White G. C. , and Garrott R. A. (1990). ‘Analysis of Wildlife Radio-tracking Data.’ (Academic Press: San Diego.)

Wolanski, E. , Moore, K. , Spagnol, S. , D’Adamo, N. , and Pattiaratchi, C. (2001). Rapid, human-induced siltation of the macro-tidal Ord River estuary, Western Australia. Estuarine, Coastal and Shelf Science 53, 717–732.
Crossref | GoogleScholarGoogle Scholar | Yerbury M. J. (1980). Long range tracking of Crocodylus porosus in Arnhem Land, northern Australia. In ‘A Handbook on Biotelemetry and Radio Tracking: Proceedings of an International Conference on Telemetry and Radio Tracking in Biology and Medicine, Oxford, 20–22 March 1979’. (Eds C. J. Amlaner, Jr, and D. W. Macdonald.) pp. 765–776. (Pergamon Press: Oxford.)